Use this forum if you have installed hMailServer and want to ask a question related to a production release of hMailServer. Before posting, please read the troubleshooting guide. A large part of all reported issues are already described in detail here.

Did it actually say {key1} or is this something you've replaced afterwards? A good name for a sub domain may be key1._domainkey. Having { or } in the selector may be a bad idea. Maybe this is why you're unable to specify it in your TXT record.

The port 25 wizard is probably confusing. It mixes up DomainKeys with DKIM which are two different things. I only have a selector record set up and that is all which is needed.

Click the ...-button next to the private key file textbox and you get to select the private key file. It shouldn't be an URL or anything else. Just select the file containing your private key.